Edexcel A-level Chem5-january-2007-qp
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- Words: 1,273
- Pages: 16
Surname
Centre No.
Initial(s)
Paper Reference
6 2 4 5
Candidate No.
0 1
Signature
Paper Reference(s)
6245/01
Examiner’s use only
Edexcel GCE
Team Leader’s use only
Chemistry Advanced
Question Leave Number Blank
Unit Test 5 (including synoptic assessment)
Tuesday 23 January 2007 – Morning Time: 1 hour 30 minutes
1 2 3 4 5
Materials required for examination Nil
Items included with question papers Nil
You may use a calculator.
Instructions to Candidates In the boxes above, write your centre number and candidate number, your surname, initial(s) and signature. Answer ALL the questions. Write your answers in the spaces provided in this question paper. Show all the steps in any calculations and state the units.
Information for Candidates The total mark for this paper is 75. The marks for individual questions and parts of questions are shown in round brackets: e.g. (2). There are 16 pages in this question paper. All blank pages are indicated. A Periodic Table is printed on the back cover of this booklet.
Advice to Candidates You are reminded of the importance of clear English and careful presentation in your answers. You will be assessed on your Quality of Written Communication in this paper.
Total This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2007 Edexcel Limited. Printer’s Log. No.
N24701A W850/R6245/57570 7/7/7/4/900
Turn over
*N24701A0116*
Leave blank
Answer ALL the questions. Write your answers in the spaces provided. 1.
(a) Consider the following table, which shows data for the reaction between reactants A and B. Expt.
[A] / mol dm–3
[B] / mol dm–3
Rate / mol dm–3s–1
1
1.0
0.50
0.0020
2
0.50
0.50
0.0010
3
0.50
1.0
0.0040
(i) Define the term order of reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (1) (ii) Determine, giving reasons, the orders of reaction with respect to A and B. Hence write the rate equation for the reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3)
2
*N24701A0216*
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(iii) Calculate a value for the rate constant and give its units. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (iv) State how, if at all, the value of the rate constant would change if the temperature were increased. ................................................................................................................................ (1)
*N24701A0316*
3
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Leave blank
Fraction of molecules with energy, E
(b) (i) Draw a Maxwell-Boltzmann curve for a sample of a gas.
Energy, E (1) (ii) On your diagram mark and label the activation energies for a catalysed and uncatalysed reaction. (1) (iii) The rate of a reaction can also be increased by raising the temperature. Describe how the Maxwell-Boltzmann curve at a higher temperature differs from the curve you have drawn in (i). ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2)
4
*N24701A0416*
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(iv) Transition metals are important industrial catalysts. Identify an industrial process involving a transition metal catalyst and name the catalyst used. Explain why many transition metals and their compounds are successful catalysts. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (v) How do the rate constants for the catalysed and uncatalysed reactions compare? ................................................................................................................................ ................................................................................................................................ (1)
Q1
(Total 15 marks)
*N24701A0516*
5
Turn over
Leave blank
2.
(a) Identify the substances and conditions used in the standard chlorine half-cell. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3) (b)
Cu+(aq) + e– → Cu(s)
E ○ = +0.52 V
Cu2+(aq) + e– → Cu+(aq)
E ○ = +0.15 V
(i) Combine the half-equations above to produce the redox equation for the disproportionation reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (1) (ii) Use the E ○ values to explain why this reaction is feasible. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (iii) Explain why the above reaction can be classified as a disproportionation reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (c) Complete the electronic configuration for a copper(I) ion, Cu+. 1s2................................................................................................................................... (1)
6
*N24701A0616*
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(d) When excess concentrated ammonia solution is added to a solution of hydrated copper(II) ions, the complex [Cu(NH3)4(H2O)2]2+ is formed. (i) State the type of reaction occurring and give the colour of the complex. Type ....................................................... Colour ................................................... (2) (ii) Explain why this complex has a colour. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (iii) Explain why copper(I) complex ions are not coloured. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (e) When concentrated hydrochloric acid is added to an aqueous solution of Cu2+ ions, the complex CuCl42– is formed. Suggest the shape of this complex, state the bond angle and suggest why it has this shape. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3)
Q2
(Total 19 marks)
*N24701A0716*
7
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Leave blank
3.
This question concerns the following reaction scheme starting from benzene, C6H6. C6H6
reaction 1
→
reaction 2
C6H5COCH3 → (phenylethanone)
C6H5C(OH)(CN)CH3
(a) Explain why the low resolution n.m.r. spectrum of benzene contains only a single peak. ....................................................................................................................................... (1) (b) (i) Identify the reagent and the catalyst needed for reaction 1. ................................................................................................................................ ................................................................................................................................ (2) (ii) What type of reaction is reaction 1? ................................................................................................................................ (1) (iii) Draw the mechanism for reaction 1.
(4) 8
*N24701A0816*
Leave blank
(c) (i) Identify the reagents needed for reaction 2. ................................................................................................................................ ................................................................................................................................ (2) (ii) What type of reaction is reaction 2? ................................................................................................................................ (1) (iii) Draw the mechanism for reaction 2.
(3)
*N24701A0916*
9
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Leave blank
(d) The product of reaction 2 is a mixture of two isomers. (i) Draw the structures of these two isomers, making their three-dimensional shape clear.
(1) (ii) What would be the effect of this mixture on monochromatic plane-polarised light? Justify your answer by reference to your mechanism in (c)(iii). ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (e) How could infra-red spectroscopy be used to show that the product of reaction 2 did not contain traces of the reactant phenylethanone? ....................................................................................................................................... (1) (Total 19 marks)
10
*N24701A01016*
Q3
BLANK PAGE
*N24701A01116*
11
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4.
(a) The following equation shows the reaction of propane with chlorine to produce 1-chloropropane. CH3CH2CH3 + Cl2 → CH3CH2CH2Cl + HCl (i) Name the mechanism of the above reaction. ................................................................................................................................ (1) (ii) State ONE essential condition. ................................................................................................................................ (1) (b) The boiling temperature of 1-chloropropane is 46 °C and that of 1-bromopropane is 71 °C. Draw a boiling temperature/composition diagram for a mixture of these two substances. Use it to explain how fractional distillation could be used to separate this mixture.
....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (5) 12
*N24701A01216*
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(c) Describe how to distinguish between pure samples of 1-chloropropane and 1-bromopropane using chemical tests. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (5) (d) Suggest which technique, mass spectrometry or low resolution n.m.r., would be more successful to distinguish between 1-chloropropane and 1-bromopropane. Justify your answer. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3)
Q4
(Total 15 marks)
*N24701A01316*
13
Turn over
5.
(a) An acidified solution of potassium manganate(VII) contains MnO4– ions, and can oxidise bromide ions, Br–, to bromine. It was found that 23.90 cm3 of 0.200 mol dm–3 potassium manganate(VII) solution was required to oxidise a solution containing 2.46 g of sodium bromide dissolved in dilute sulphuric acid. Calculate the ratio of the number of moles of manganate(VII) ions reacting to the number of moles of bromide ions reacting. Hence write the equation for the oxidation of bromide ions by manganate(VII) ions in acid solution.
(5)
14
*N24701A01416*
Leave blank
Leave blank
(b) Acidified potassium manganate(VII) solution can be safely stored in containers made of poly(ethene). (i) Suggest a property of poly(ethene) which makes it suitable for the storage of this solution. ................................................................................................................................ (1) (ii) Explain ONE environmental problem which may be caused by the disposal of a poly(ethene) container. ................................................................................................................................ ................................................................................................................................ (1)
Q5
(Total 7 marks) TOTAL FOR PAPER: 75 MARKS END
*N24701A01516*
15
16
*N24701A01616*
Centre No.
Initial(s)
Paper Reference
6 2 4 5
Candidate No.
0 1
Signature
Paper Reference(s)
6245/01
Examiner’s use only
Edexcel GCE
Team Leader’s use only
Chemistry Advanced
Question Leave Number Blank
Unit Test 5 (including synoptic assessment)
Tuesday 23 January 2007 – Morning Time: 1 hour 30 minutes
1 2 3 4 5
Materials required for examination Nil
Items included with question papers Nil
You may use a calculator.
Instructions to Candidates In the boxes above, write your centre number and candidate number, your surname, initial(s) and signature. Answer ALL the questions. Write your answers in the spaces provided in this question paper. Show all the steps in any calculations and state the units.
Information for Candidates The total mark for this paper is 75. The marks for individual questions and parts of questions are shown in round brackets: e.g. (2). There are 16 pages in this question paper. All blank pages are indicated. A Periodic Table is printed on the back cover of this booklet.
Advice to Candidates You are reminded of the importance of clear English and careful presentation in your answers. You will be assessed on your Quality of Written Communication in this paper.
Total This publication may be reproduced only in accordance with Edexcel Limited copyright policy. ©2007 Edexcel Limited. Printer’s Log. No.
N24701A W850/R6245/57570 7/7/7/4/900
Turn over
*N24701A0116*
Leave blank
Answer ALL the questions. Write your answers in the spaces provided. 1.
(a) Consider the following table, which shows data for the reaction between reactants A and B. Expt.
[A] / mol dm–3
[B] / mol dm–3
Rate / mol dm–3s–1
1
1.0
0.50
0.0020
2
0.50
0.50
0.0010
3
0.50
1.0
0.0040
(i) Define the term order of reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (1) (ii) Determine, giving reasons, the orders of reaction with respect to A and B. Hence write the rate equation for the reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3)
2
*N24701A0216*
Leave blank
(iii) Calculate a value for the rate constant and give its units. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (iv) State how, if at all, the value of the rate constant would change if the temperature were increased. ................................................................................................................................ (1)
*N24701A0316*
3
Turn over
Leave blank
Fraction of molecules with energy, E
(b) (i) Draw a Maxwell-Boltzmann curve for a sample of a gas.
Energy, E (1) (ii) On your diagram mark and label the activation energies for a catalysed and uncatalysed reaction. (1) (iii) The rate of a reaction can also be increased by raising the temperature. Describe how the Maxwell-Boltzmann curve at a higher temperature differs from the curve you have drawn in (i). ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2)
4
*N24701A0416*
Leave blank
(iv) Transition metals are important industrial catalysts. Identify an industrial process involving a transition metal catalyst and name the catalyst used. Explain why many transition metals and their compounds are successful catalysts. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (v) How do the rate constants for the catalysed and uncatalysed reactions compare? ................................................................................................................................ ................................................................................................................................ (1)
Q1
(Total 15 marks)
*N24701A0516*
5
Turn over
Leave blank
2.
(a) Identify the substances and conditions used in the standard chlorine half-cell. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3) (b)
Cu+(aq) + e– → Cu(s)
E ○ = +0.52 V
Cu2+(aq) + e– → Cu+(aq)
E ○ = +0.15 V
(i) Combine the half-equations above to produce the redox equation for the disproportionation reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (1) (ii) Use the E ○ values to explain why this reaction is feasible. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (iii) Explain why the above reaction can be classified as a disproportionation reaction. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (c) Complete the electronic configuration for a copper(I) ion, Cu+. 1s2................................................................................................................................... (1)
6
*N24701A0616*
Leave blank
(d) When excess concentrated ammonia solution is added to a solution of hydrated copper(II) ions, the complex [Cu(NH3)4(H2O)2]2+ is formed. (i) State the type of reaction occurring and give the colour of the complex. Type ....................................................... Colour ................................................... (2) (ii) Explain why this complex has a colour. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (iii) Explain why copper(I) complex ions are not coloured. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (2) (e) When concentrated hydrochloric acid is added to an aqueous solution of Cu2+ ions, the complex CuCl42– is formed. Suggest the shape of this complex, state the bond angle and suggest why it has this shape. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3)
Q2
(Total 19 marks)
*N24701A0716*
7
Turn over
Leave blank
3.
This question concerns the following reaction scheme starting from benzene, C6H6. C6H6
reaction 1
→
reaction 2
C6H5COCH3 → (phenylethanone)
C6H5C(OH)(CN)CH3
(a) Explain why the low resolution n.m.r. spectrum of benzene contains only a single peak. ....................................................................................................................................... (1) (b) (i) Identify the reagent and the catalyst needed for reaction 1. ................................................................................................................................ ................................................................................................................................ (2) (ii) What type of reaction is reaction 1? ................................................................................................................................ (1) (iii) Draw the mechanism for reaction 1.
(4) 8
*N24701A0816*
Leave blank
(c) (i) Identify the reagents needed for reaction 2. ................................................................................................................................ ................................................................................................................................ (2) (ii) What type of reaction is reaction 2? ................................................................................................................................ (1) (iii) Draw the mechanism for reaction 2.
(3)
*N24701A0916*
9
Turn over
Leave blank
(d) The product of reaction 2 is a mixture of two isomers. (i) Draw the structures of these two isomers, making their three-dimensional shape clear.
(1) (ii) What would be the effect of this mixture on monochromatic plane-polarised light? Justify your answer by reference to your mechanism in (c)(iii). ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ (3) (e) How could infra-red spectroscopy be used to show that the product of reaction 2 did not contain traces of the reactant phenylethanone? ....................................................................................................................................... (1) (Total 19 marks)
10
*N24701A01016*
Q3
BLANK PAGE
*N24701A01116*
11
Turn over
Leave blank
4.
(a) The following equation shows the reaction of propane with chlorine to produce 1-chloropropane. CH3CH2CH3 + Cl2 → CH3CH2CH2Cl + HCl (i) Name the mechanism of the above reaction. ................................................................................................................................ (1) (ii) State ONE essential condition. ................................................................................................................................ (1) (b) The boiling temperature of 1-chloropropane is 46 °C and that of 1-bromopropane is 71 °C. Draw a boiling temperature/composition diagram for a mixture of these two substances. Use it to explain how fractional distillation could be used to separate this mixture.
....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (5) 12
*N24701A01216*
Leave blank
(c) Describe how to distinguish between pure samples of 1-chloropropane and 1-bromopropane using chemical tests. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (5) (d) Suggest which technique, mass spectrometry or low resolution n.m.r., would be more successful to distinguish between 1-chloropropane and 1-bromopropane. Justify your answer. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... (3)
Q4
(Total 15 marks)
*N24701A01316*
13
Turn over
5.
(a) An acidified solution of potassium manganate(VII) contains MnO4– ions, and can oxidise bromide ions, Br–, to bromine. It was found that 23.90 cm3 of 0.200 mol dm–3 potassium manganate(VII) solution was required to oxidise a solution containing 2.46 g of sodium bromide dissolved in dilute sulphuric acid. Calculate the ratio of the number of moles of manganate(VII) ions reacting to the number of moles of bromide ions reacting. Hence write the equation for the oxidation of bromide ions by manganate(VII) ions in acid solution.
(5)
14
*N24701A01416*
Leave blank
Leave blank
(b) Acidified potassium manganate(VII) solution can be safely stored in containers made of poly(ethene). (i) Suggest a property of poly(ethene) which makes it suitable for the storage of this solution. ................................................................................................................................ (1) (ii) Explain ONE environmental problem which may be caused by the disposal of a poly(ethene) container. ................................................................................................................................ ................................................................................................................................ (1)
Q5
(Total 7 marks) TOTAL FOR PAPER: 75 MARKS END
*N24701A01516*
15
16
*N24701A01616*
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